The present invention generally relates to tape cassettes, and more particularly to a tape cassette having a transparent window which enables visual detection of a wound state of a magnetic tape with respect to a supply reel and a take-up reel of the tape cassette, from outside the tape cassette.
Generally, a tape cassette which is used with respect to a recording and reproducing apparatus such as a video tape recorder, accommodates a magnetic tape which has transparent tapes connected at ends thereof. When the tape cassette is loaded into the video tape recorder, the tape is loaded unto a predetermined tape path so that the tape opposes an optical tape end detector of the video tape recorder. If the transparent tape is drawn out of one of a supply reel and a take-up reel of the tape cassette during a mode of the video tape recorder in which the tape travels, the transparent tape is detected by the optical tape end detector, and the tape travel is stopped to put the video tape recorder in a stop mode. Generally, the optical tape end detector comprises a lamp which relatively enters within the tape cassette when the tape cassette is loaded into the video tape recorder, and a photocell which opposes an opening in a side wall of the tape cassette when the tape cassette is loaded. In addition, the tape cassette has a transparent window which enables visual detection of a wound state of the tape with respect to the reels of the tape cassette, such as the remaining quantity of tape on the reels, from outside the tape cassette. The transparent window is generally located at a position opposing the reels, that is, at a location which is substantially at the center with respect to the front and rear of the tape cassette.
Recently, various compact type tape cassettes have been proposed, which are designed so as to enable downsizing of the video tape recorder. However, if the tape cassette is simply downsized with the above transparent window located at the position opposing the reels, the opening in the side wall of the tape cassette will be located quite close to the transparent window. In other words, the distance between the transparent window and the opening in the side wall of the tape cassette, will become considerably small. Accordingly, in a state where the compact type tape cassette is loaded into the video tape recorder, a part of an external light may pass through the transparent window and reach the photocell of the optical tape end detector, according to the angle of incidence and the direction of the impinging light with respect to the tape cassette. Thus, the external light may pass through the transparent window and the opening in the side wall of the tape cassette, and finally reach the photocell, regardless of the remaining quantity of tape on the reels. In such a case, the optical tape end detector will erroneously detect that the transparent tape has been reached, although the magnetic tape was actually detected and the transparent tape was never detected. Therefore, the conventional tape cassette had a problem in that the optical tape end detector could easily carry out an erroneous detection of the transparent tape, if the conventional tape cassette is simply downsized.
Further, the problem related to the erroneous detecting operation of the optical tape end detector will be eliminated if the transparent window is not provided in the tape cassette. However, without the transparent window, it will be impossible to visually detect the wound state of a magnetic tape with respect to the reels of the tape cassette, from outside the tape cassette, and the omission of this feature would be inconvenient for the user.